Eighty parasitologically confirmed cases of visceral leishmaniasis (kala-azar) in Bihar, India, were treated daily with 20 mg sodium stibogluconate/kg for 30 days, to assess the current efficacy and toxicity of this 30-day regimen. Clinical and parasitological cure was obtained in 48 (60%) of the patients. However, 26 (33%) patients did not respond to the first course of treatment (primary unresponsiveness), two relapsed after initial clinical and parasitological cure, and two were withdrawn from the study (one on day 6 of treatment because of cardiotoxicity in the form of supraventricular tachycardia and the other on day 24 because of severe loss of appetite). All 30 patients who were not entirely cured with sodium stibogluconate were successfully treated with amphotericin B. Electrocardiographic changes occurred in many of the patients as the result of treatment with sodium stibogluconate. Diminution in the height of the T wave was seen in 32 (40%), inversion of the T wave (Minnesota code 5-1, 5-2) in seven (9%), elevation of the ST segment (Minnesota code 4-1) in three (4%), prolonged QT interval (compared with baseline findings) in six (8%), and diminution in the height of the P, R and T waves in two (3%). Cardiac arrhythmia occurred in five patients (6%), supraventricular arrhythmia (coarse atrial fibrillation) occurred in one patient and ventricular tachycardia, ventricular fibrillation, torsade de pointes and multifocal ventricular ectopics occurred in the four patients (5%) who died of cardiotoxicity. Minor side-effects, such as pain at the site of injection (two cases), mild diminution in appetite (12 cases), metallic taste in mouth (six cases), and joint pain (two cases), were also observed. It was concluded that the efficacy of sodium stibogluconate in the study area has declined over the years and that its toxicity has increased. A more efficacious, safer and cheaper, alternative drug is required as the first line of treatment of kala-azar.