A tamper-resistant envelope (100; 200; 300; 400; 500) comprising: a first and a second panel (102, 104; 202, 204; 402, 404; 502, 504) joined together along at least one tamper-evident seam (103; 503) to form a pocket therebetween having an opening, said tamper-evident seam (103; 503) having a width configured to provide at least one tamper-evident feature, said tamper-evident feature including at least one of embossing and perforations (116, 118) in said seam formed of both said first and second panels (102, 104; 202, 204; 402, 404; 502, 504), wherein said tamper-evident seam (103; 503) is provided with at least one of said embossing and perforations (116, 118) formed through said first and second panels (102, 104; 202, 204; 402, 404; 502, 504); and a flap (106; 206; 306; 506) comprising a tamper-evident adhesive (114; 314; 514), said flap (106; 206; 306; 506) distally connected to the first panel (104; 204; 404; 504) along a fold line, wherein said adhesive (114; 314; 514) is disposed on a single side of said fold line, said flap (106; 206; 306; 506) adapted to adhere to at least a portion of the first panel (104; 204; 404; 504) and at least a portion of the second panel (102; 202; 402; 504) when folded along the fold line, said adhesive (114; 314; 514) configured to allow said flap (106; 206; 306; 506) to substantially seal said opening, wherein said adhesive (114; 314; 514) is adapted to change a color as a result of tampering with the adhesive (114; 314; 514); wherein said first and second panels (102, 104; 202, 204; 402, 404; 502, 504) include a laminate film susceptible to a wetter, said laminate film configured to change color when exposed to the wetter; wherein said adhesive (114; 314; 514) comprises an adhesive film configured to adhere to a portion of said tamper-evident feature including said at least one tamper-evident seam (103; 503) formed of said joined-together first and second panels (102, 104; 202, 204; 402, 404; 502, 504); and wherein said adhesive film, when adhered to a portion of said tamper-evident feature including said at least one tamper-evident seam (103; 503) formed of said joined-together first and second panels (102, 104; 202, 204; 402, 404; 502, 504), is configured to prevent access to said sealed opening from any direction using a mechanical means configured to be inserted under said flap (106; 206; 306; 506) for opening said flap (106; 206; 306; 506). a first and a second panel (102, 104; 202, 204; 402, 404; 502, 504) joined together along at least one tamper-evident seam (103; 503) to form a pocket therebetween having an opening, said tamper-evident seam (103; 503) having a width configured to provide at least one tamper-evident feature, said tamper-evident feature including at least one of embossing and perforations (116, 118) in said seam formed of both said first and second panels (102, 104; 202, 204; 402, 404; 502, 504), wherein said tamper-evident seam (103; 503) is provided with at least one of said embossing and perforations (116, 118) formed through said first and second panels (102, 104; 202, 204; 402, 404; 502, 504); and a flap (106; 206; 306; 506) comprising a tamper-evident adhesive (114; 314; 514), said flap (106; 206; 306; 506) distally connected to the first panel (104; 204; 404; 504) along a fold line, wherein said adhesive (114; 314; 514) is disposed on a single side of said fold line, said flap (106; 206; 306; 506) adapted to adhere to at least a portion of the first panel (104; 204; 404; 504) and at least a portion of the second panel (102; 202; 402; 504) when folded along the fold line, said adhesive (114; 314; 514) configured to allow said flap (106; 206; 306; 506) to substantially seal said opening, wherein said adhesive (114; 314; 514) is adapted to change a color as a result of tampering with the adhesive (114; 314; 514); wherein said first and second panels (102, 104; 202, 204; 402, 404; 502, 504) include a laminate film susceptible to a wetter, said laminate film configured to change color when exposed to the wetter; wherein said adhesive (114; 314; 514) comprises an adhesive film configured to adhere to a portion of said tamper-evident feature including said at least one tamper-evident seam (103; 503) formed of said joined-together first and second panels (102, 104; 202, 204; 402, 404; 502, 504); and wherein said adhesive film, when adhered to a portion of said tamper-evident feature including said at least one tamper-evident seam (103; 503) formed of said joined-together first and second panels (102, 104; 202, 204; 402, 404; 502, 504), is configured to prevent access to said sealed opening from any direction using a mechanical means configured to be inserted under said flap (106; 206; 306; 506) for opening said flap (106; 206; 306; 506).