Abstract Introduction Cancer patients with neutropenia (<1500 cell/mm3 absolute neutrophil count [ANC]) are at high risk of febrile neutropenia and serious complications which can cause the delay treatment, reduction of chemotherapy dose, leading to morbidity and mortality. We lack of information of the prevalence of neutropenia in Thailand and its' consequences. Thus, this cross-sectional study aimed to investigate the prevalence of neutropenia at a provincial hospital in northern Thailand. Methods We retrospectively reviewed electronic medical records of cancer patients with solid tumor and receiving chemotherapy from September 2018 to October 2019. Results A total of 248 cancer patients (79 men, 169 women, mean age of 58.36±12.03) were included. The top 3 cancers were colon, breast and lung cancer (50.53%, 34.33%, 6.88%). They received chemotherapy 1,803 cycles of treatment. The top 3 regimens of treatment were FOLFOX (oxaliplatin/ fluorouracil/ leucovorin), AC (doxorubicin/ cyclophosphamide) and paclitaxel (42.65%, 17.75%, 9.67%). The prevalence of neutropenia (<1500 cell/mm3) was 264 episodes: 64 episodes of ANC 1,000-1,500 cell/mm3 (3.55%); 172 episodes of ANC 500-1,000 cell/mm3 (9.54%); and 28 episodes of ANC <500 cell/mm3 (1.55%). Most of them were postponed the treatment, but 16 episodes were still received chemotherapy. The dose of chemotherapy in 78 episodes were decreased and 16 episodes were related to the treatment of febrile neutropenia. The treatment of febrile neutropenia chemotherapy patients was 8 + 3 days with an average of US$ 400 per person, per cost of treatment. Conclusions We found that the effects of neutropenia in chemotherapy patients were delayed treatment, dose reduction and a major risk factor of febrile neutropenia. This decreased the efficiency of chemotherapy in patients with cancer. The result should be informed and encouraged our patient care team to develop practical action for prevention and management of serious neutropenic events. Key messages The result should be informed and encouraged our patient care team to develop practical action for prevention and management of serious neutropenic events. If we can manage cancer patients with neutropenia, the cost of treatment for serious febrile neutropenia and other complications will be reduced.