Motor-vehicle front structure, comprising: - a pair of longitudinal struts, having front ends to which two strut plates are secured, - a front cross-member placed in front of the strut plates and having ends provided with two rearwardly facing cross-member plates, which are rigidly connected to said strut plates, wherein each cross-member plate is a crash-box plate, connected to said front cross-member with the interposition of a crash-box structure, - wherein said crash-box plates are also connected to a lower auxiliary cross-member, through two respective supports, each of which has its upper end connected to the respective crash-box plate and its lower end connected to a respective end of the lower auxiliary cross-member, - a front-end unit for supporting one or more motor-vehicle auxiliary components, said front-end unit being interposed between the front cross-member and the strut plates and including at least an upper cross-member constituted of plastic material, - wherein said crash-box plates are connected directly to said strut plates, with no interposition of elements forming part of the front-end unit therebetween, characterized in that: - said front-end unit includes, beyond said upper cross-member, at least a lower cross-member also constituted of plastic material, - said upper and lower cross-members (M1, M2) of the front-end unit are constituted by elements which are separated from each other and both connected at their ends to said crash-box plates, the upper cross-member of the front-end unit being an element of plastic material having ends screwed directly to the crash-box plates, and the lower cross-member of the front-end unit being connected to the crash-box plates through said supports, and in that said supports are comprised of two L-shaped steel sheets, having vertical portions bolted to the lower ends of said crash-box plates and horizontal portions to which the ends of said lower crosspiece of the front-end unit are screwed - a pair of longitudinal struts, having front ends to which two strut plates are secured, - a front cross-member placed in front of the strut plates and having ends provided with two rearwardly facing cross-member plates, which are rigidly connected to said strut plates, - wherein said crash-box plates are also connected to a lower auxiliary cross-member, through two respective supports, each of which has its upper end connected to the respective crash-box plate and its lower end connected to a respective end of the lower auxiliary cross-member, - a front-end unit for supporting one or more motor-vehicle auxiliary components, said front-end unit being interposed between the front cross-member and the strut plates and including at least an upper cross-member constituted of plastic material, - wherein said crash-box plates are connected directly to said strut plates, with no interposition of elements forming part of the front-end unit therebetween, - said front-end unit includes, beyond said upper cross-member, at least a lower cross-member also constituted of plastic material, - said upper and lower cross-members (M1, M2) of the front-end unit are constituted by elements which are separated from each other and both connected at their ends to said crash-box plates, the upper cross-member of the front-end unit being an element of plastic material having ends screwed directly to the crash-box plates, and the lower cross-member of the front-end unit being connected to the crash-box plates through said supports, and in that said supports are comprised of two L-shaped steel sheets, having vertical portions bolted to the lower ends of said crash-box plates and horizontal portions to which the ends of said lower crosspiece of the front-end unit are screwed