Data tabulations for a carcinogenesis bioassay of condensed effluents obtained from iron foundry casting operations that used hamsters as the test species are presented. Gross pathological observations in the abdominal cavity, adrenals, brain, diaphragm, gallbladder, heart, intestinal tract, kidneys, liver, lungs and bronchi, lymph nodes, pancreas, prostate, seminal vesicles, skin and subcutis, salivary gland, spleen, stomach, trachea, testes, thoracic cavity, thymus, thyroid, urinary bladder, parathyroids, pituitary, uterus, or ovaries in males and females are summarized. Lesions observed in respiratory tract tissue masses in males and females are tabulated. Histopathological observations in the skin, thigh muscle, salivary gland, mandibular lymph node, sciatic nerve, brain, pituitary, adrenals, thymus, stomach, duodenum, jejunum, cecum, colon, rectum, mesenteric lymph node, ileum, larynx, trachea, thyroid, lung, bronchial lymph nodes, main stem bronchi, liver, gallbladder, spleen, pancreas, prostate, seminal vesicles, sternum and rib junction, femur and bone marrow, nasal cavity, esophagus, parathyroid, heart, kidneys, urinary bladder, ovaries, or uterus in males and females are presented. The results of Fisher's analysis for significance of tumor bearing animals are summarized.