['Microscopy centres in Tiruvallur District, Tamil Nadu, India, implementing DOTS.', 'To know whether washing new glass slides in dichromate solution is essential for effective sputum acid-fast bacilli microscopy.', 'Two direct smears were prepared from each of 1750 sputum samples. One was made on dichromate solution-cleaned new glass slides and the other was made on unwashed new glass slides. The smears were blinded and examined.', 'Of the 1750 specimens, 13.5% and 13.08% were positive for AFB using washed and unwashed slides, respectively (P = 0.12). The concordance between these two (including one grade above and one below) was 98.7%.'] Does washing of new microscopic glass slides in dichromate solution influence sputum AFB smear results?