Iodine is important element for human growth and development. Lack or excess of this element result human health problems. Naturally, low dietary supply of iodine is primary cause of iodine deficiency, typically in lack iodine environments .. Climate, topography, and material entity of area contribute iodine in environment. Iodine contain ofwater is a reliable indicator of the iodine contain in environment. Measurement of iodine contain in groundwater and recording of conditions of it s well/spring of groundwater is important to Know correlation between iodine contain and local condition of it s spring/well. This research will describes iodine contain in groundwater in western slope of Merapi Mountain, and it s relation with altitude ofit s spring. This research designed cross-sectionall-y. Sample of groundwater was taken from it s spring/well at western slo pe of Merapi Mountain. Location coordinates, altitude, and condition of spring/well was recorded. Iodine contain in groundwater was measured by spectrophotometer method. Iodine contain in groundwater at western slope of Merapi Mountain range from 0 ug/L to 8 ug/L and correlate with altitude in negative way.Key words : iodine, iodine contain in groundwater, altitude.