Information on 217,174 microscopically diagnosed cancers diagnosed in 2001–2002 was collected from pathology laboratories in 68 districts across India. Data collection took place primarily via the Internet. Average annual age-adjusted incidence rates for microscopically diagnosed cases (MAAR) by gender and site were calculated for each of the 593 districts in the country. The rates were compared to those from established population based cancer registries (PBCR). In 82 districts, the MAAR for ‘all cancer sites’ was above a “completeness” threshold of 36.2/100,000 (based on results of a rural PBCR). The results confirmed some known features of the geography of cancer in India, and brought to light new ones. Cancers of the mouth and tongue are particularly frequent in both genders in the southern states. Very high rates of nasopharynx cancer were found in the northeastern states (Nagaland, Manipur). There was clear geographic correlation between the rates of cervical and penile cancer, and a high rate of stomach and lung cancer (in both genders) in many districts of Mizoram State. The area of high risk for gallbladder cancer seems larger than suspected previously, involving a wide band of northern India. There is a belt of high incidence of thyroid cancer in females in southwest coastal districts. Other than identifying possible existence of high-risk areas of specific cancers, our study has recognized places where PBCR could be established. The study was remarkably cost-effective and the electronic data-capture methodology provides a model for health informatics in the setting of a developing country.