Fundamental pathologic cianges of secondary syphilid are said to be swelling and proliferation of endothelials and a predominantly parivascular infiltrates composed chiefly of lymphoid cells and plasma cells. But recentIy this theory has heen challenged. We present bistologic observation made on 10 patients who agreed to go through a biopsy, during 2 years period. from 1975 to l977. Male to female ratio was 9: 1 The age of patient ranged from 20 to 33, with a mean of 26. 8. The duration of lesion before the visit to the department ranged frorn 6 weeks to 20 weeks, with a mean of 11.9. The lesions in 2 were classified as macule, 3 as papule (1 as moist papule), and 5 as papulo-squamous lesions. The VDRL titer was higher in papular type. Dark fieId examination was performed on all patient and 6 showed positive result. The edidermal changes consist of hyperkeratosis (in 6 cases), parakeratosis (in 5), acanthosis (in 6), elongation of rete ridges (in 8) and exocytosis (in 3). The dermis showed mild to severe perivascular infiltration consist chiefly of lymphoid cells and histiocytic cells (in 10), plama cells (in 7), eosinophils (in 4), neutrophils (in 2), chromatophores (in 4), extra vasation of RBC (in 5), and dilated bload vessels endothelial swellings (in 8). Of particular interest was the finding that plasma cell infiltration is more pronounced at the lower portion of dermal infiltrate and in 3 cases plasma cell infiltration was totally absent. Vascular changes were seen in 8 cases.