A seroepidemiological study of Toxoplasma gondii was carried out in four municipalities of Havana Province from October 1990 to April 1991 using a 10µL ultra micro-ELISA. We tested 362 serum samples, from pregnant women, and 71% of toxoplasmic infection was found. Toxoplasmic infection was more frequent in women living in rural zones having domestics contacts with cats. The relationship of toxoplasmic infection and spontaneous abortion antecedent in this group was analyzed but no statistically significant differences were found.