Hyde Park civic leader Louise C. Walker, who gave her time and energy to such interests as the Junior League of Cincinnati and Cancer Family Care, died at her home Friday. She was 75. Mrs. Walker was active in civic affairs, holding leadership positions with the Junior League, as well as taking a leading role in the Cincinnati Branch of the Needlework Guild of America, the Symphony Ball and the United Fine Arts Fund. She was an active member of Hyde Park Community United Methodist Church for many years, and paid special attention to the church Altar Guild and Building Expansion Program. She played an instrumental role in the church's chapel construction in the 1960s. Beyond those involvements, Mrs. Walker also focused much of her energy on the formative fund-raising efforts for Cancer Family Care and Christ Hospital. According to her daughters, her ''devotion to family, and the wise counsel and abundant enthusiasm that she brought to community projects, were her hallmarks. Community service was very important to her. She carried out tasks with a sense of thoroughness and loveliness.'' She leaves her husband, William Lee Walker; daughters, Cynthia Walker Churchin of Joplin, Mo., Louise Walker Borden and Margaret Walker Comey, both of Cincinnati; a sister, Cynthia Storrs of Cincinnati; and eight grandchildren.